1 88 Journal gf Comparative Neurology. 



We have been led to mention these facts, since Berkley 

 has quite recently described two distinct kinds of nerve fibers, 

 with distinctive nerve endings in heart muscle. In the inter- 

 muscular plexus, these nerve fibers are described by him as 

 follows : 



1. Varicose nerves of "longitudinal main fibers with 

 right angled branching ; the terminations being on short ramus- 

 cules from the finer filaments." These fibers are stained a 

 " brownish black " in the chrome-silver method used by Berk- 

 ley. "The end-apparatus of the varicose network is usually 

 very simple, being represented almost without exception by a 

 minute ball-like arrangement at the terminal point of the end 

 branches." 



2. Fibers that stain a "uniform jet black" and "run for a 

 long distance with but very few side branches and exceedingly 

 rarely develop upon themselves any knotty thickenings." 

 "They are characterized hot uncommonly by the presence of 

 a round or elongated ball not far distant from the end appara- 

 tus. " ' 'The end apparatus of the second type of fiber, presents, 

 in complete contrast to the fibers of the network, an end appa- 

 ratus of complex form." Fig. 4, 5 and 6, of Berkley's article 

 show these more complex endings, which are of pennate form, 

 some simpler, others more complex. The account here given 

 has reference to Berkley's observations on the mouse heart. 

 In his description of the endings in the dog's heart, he states 

 that they correspond in the main with those found in the mouse. 

 In about 1 20 successfully stained sections from the heart of the 

 dog, Berkley found about 10 endings of a more complex nature. 

 "These expansions were of considerable size, covering the 

 breadth of two or three muscular fibers and varied slightly in 

 form." Berkley's interpretation of these more complex end- 

 ings and also his opinion of the bulbar enlargement on the fibre 

 thus ending, may be given in his own words: "In all these, 

 nodal structures, which are always most deeply stained, it is im- 

 possible to discover anything of a cellular nature, yet, as they 

 are several times larger than any of the ordinary varicose knots 

 that are met with on the fibers of the first class, and have little 



